Waterproof sound-transmitting membrane, sound-transmitting member, and electrical device

Abstract

A waterproof sound-transmitting membrane ( 1 ) of the present invention includes a porous membrane ( 11 ) containing polytetrafluoroethylene as a main component and a supporting member ( 12 ) that supports the porous membrane ( 11 ). The supporting member ( 12 ) is joined to the porous membrane ( 11 ) placed thereon and is not subjected to stretching after the porous membrane ( 11 ) is placed thereon. The supporting member ( 12 ) is a mesh or a net having a fiber diameter of 45 to 60 μm and an opening size of 700 to 1100 μm across the supporting member ( 12 ). The waterproof sound-transmitting membrane ( 1 ) has a water entry pressure of 20 kPa or more as measured according to the method B (high hydraulic pressure method) of JIS L 1092.

The invention claimed is: 
     
       1. A waterproof sound-transmitting membrane comprising:
 a porous membrane containing polytetrafluoroethylene as a main component; and 
 a supporting member that is joined to the porous membrane placed thereon and supports the porous membrane, the supporting member being not subjected to stretching after the porous membrane is placed thereon, 
 wherein the supporting member is a mesh or a net having a fiber diameter of 45 to 60 μm and an opening size of 700 to 1100 μm across the supporting member, and 
 a water entry pressure of the waterproof sound-transmitting membrane is 20 kPa or more as measured according to the method B (high hydraulic pressure method) of JIS L1092. 
 
     
     
       2. The waterproof sound-transmitting membrane according to  claim 1 , wherein an insertion loss for sounds of 3000 Hz is 5 dB or less. 
     
     
       3. The waterproof sound-transmitting membrane according to  claim 1 , wherein the supporting member is formed of a resin material having a Young's modulus of 0.2 to 7.0 GPa. 
     
     
       4. The waterproof sound-transmitting membrane according to  claim 1 , wherein the porous membrane has a surface density of 2.0 to 10.0 g/m 2 . 
     
     
       5. A sound-transmitting member comprising:
 the waterproof sound-transmitting membrane according to  claim 1 ; and 
 a membrane supporting member that supports the waterproof sound-transmitting membrane. 
 
     
     
       6. An electrical device comprising a sound emitter or a sound receiver, wherein
 the waterproof sound-transmitting membrane according to  claim 1  is disposed over an opening provided in a housing of the electrical device at a position corresponding to the sound emitter or the sound receiver. 
 
     
     
       7. An electrical device comprising a sound emitter or a sound receiver, wherein
 the sound-transmitting member according to  claim 5  is disposed over an opening provided in a housing of the electrical device at a position corresponding to the sound emitter or the sound receiver.